using System;
using System.Text;

using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1
{
	/**
	 * Der UniversalString object.
	 */
	public class DerUniversalString
		: DerStringBase
	{
		private static readonly char[] table = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

		private readonly byte[] str;

		/**
		 * return a Universal string from the passed in object.
		 *
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static DerUniversalString GetInstance(
			object obj)
		{
			if (obj == null || obj is DerUniversalString)
			{
				return (DerUniversalString)obj;
			}

			throw new ArgumentException("illegal object in GetInstance: " + obj.GetType().Name);
		}

		/**
		 * return a Universal string from a tagged object.
		 *
		 * @param obj the tagged object holding the object we want
		 * @param explicitly true if the object is meant to be explicitly
		 *              tagged false otherwise.
		 * @exception ArgumentException if the tagged object cannot
		 *               be converted.
		 */
		public static DerUniversalString GetInstance(
			Asn1TaggedObject	obj,
			bool				isExplicit)
		{
			Asn1Object o = obj.GetObject();

			if (isExplicit || o is DerUniversalString)
			{
				return GetInstance(o);
			}

			return new DerUniversalString(Asn1OctetString.GetInstance(o).GetOctets());
		}

		/**
		 * basic constructor - byte encoded string.
		 */
		public DerUniversalString(
			byte[] str)
		{
			if (str == null)
				throw new ArgumentNullException("str");

			this.str = str;
		}

		public override string GetString()
		{
			StringBuilder buffer = new StringBuilder("#");
			byte[] enc = GetDerEncoded();

			for (int i = 0; i != enc.Length; i++)
			{
				uint ubyte = enc[i];
				buffer.Append(table[(ubyte >> 4) & 0xf]);
				buffer.Append(table[enc[i] & 0xf]);
			}

			return buffer.ToString();
		}

		public byte[] GetOctets()
		{
			return (byte[]) str.Clone();
		}

		internal override void Encode(
			DerOutputStream derOut)
		{
			derOut.WriteEncoded(Asn1Tags.UniversalString, this.str);
		}

		protected override bool Asn1Equals(
			Asn1Object asn1Object)
		{
			DerUniversalString other = asn1Object as DerUniversalString;

			if (other == null)
				return false;

//			return this.GetString().Equals(other.GetString());
			return Arrays.AreEqual(this.str, other.str);
		}
	}
}
